Weird Clutch Wear
Thread Starter
Instructor
Joined: Sep 2008
Posts: 216
Likes: 0
From: Eugene OR
Weird Clutch Wear
Looking for some advice....
I installed a new clutch a couple weeks ago and ended up with some chatter. I assumed I had a bad throwout bearing out of the box, but I tore it down again (after about five miles of driving) and the throwout bearing looks fine. The only strange thing that I can find is this circular wear pattern on the flywheel side of the clutch disk.
I had the flywheel turned by a reputable machine shop, so that shouldn't be an issue. I also replaced the pilot bushing during the job.
Anybody have any idea if this wear pattern is indicative of a problem? I have no idea what was causing the chatter and I'm a little afraid to slap it back together as I don't want to end up with the same problem again.
Thanks!
I installed a new clutch a couple weeks ago and ended up with some chatter. I assumed I had a bad throwout bearing out of the box, but I tore it down again (after about five miles of driving) and the throwout bearing looks fine. The only strange thing that I can find is this circular wear pattern on the flywheel side of the clutch disk.
I had the flywheel turned by a reputable machine shop, so that shouldn't be an issue. I also replaced the pilot bushing during the job.
Anybody have any idea if this wear pattern is indicative of a problem? I have no idea what was causing the chatter and I'm a little afraid to slap it back together as I don't want to end up with the same problem again.
Thanks!
Race Director
Joined: May 2006
Posts: 18,755
Likes: 2,589
this article lists a number of causes of chatter, what brand is the disc?
http://www.carcraft.com/techarticles...h/viewall.html
http://www.carcraft.com/techarticles...h/viewall.html
Thread Starter
Instructor
Joined: Sep 2008
Posts: 216
Likes: 0
From: Eugene OR
this article lists a number of causes of chatter, what brand is the disc?
http://www.carcraft.com/techarticles...h/viewall.html
http://www.carcraft.com/techarticles...h/viewall.html
The clutch kit is a Zoom from Summit. You can check it out here.
I noticed that the article says that an 11" clutch plate is not compatible with a stock flywheel:
"For example, a GM 11-inch clutch disc has a roughly 16 percent larger surface area than the smaller GM 10.5-inch assembly. This increased size does work well, but the tradeoff is the larger clutch requires a larger-diameter flywheel that is heavier and is also roughly 1-inch-larger diameter, requiring more power to accelerate.
Is that really the case? Because pairing an 11" clutch plate with a stock flywheel is exactly what I put together.
Thread Starter
Instructor
Joined: Sep 2008
Posts: 216
Likes: 0
From: Eugene OR
Contradictory evidence here:
2 Flywheel sizes:
153 tooth, 12.75” diameter. Used on 350ci and smaller engines.
168 tooth, 14” diameter. Used on SBC and BBC, 400ci and larger
There are 3 clutch sizes:
10.4”; the most common (aka the “10 1/2” clutch)
11”
12”; for truck applications
The 10.4” and 11” clutch can be used on either flywheel, and your choice depends on the clutch pressure plate bolt pattern. Generally, the 11” clutch will only fit on a 168 tooth flywheel, however, aftermarket companies do sell a pressure plate for the 153 tooth flywheel and and 11” disc.
What the heck?
2 Flywheel sizes:
153 tooth, 12.75” diameter. Used on 350ci and smaller engines.
168 tooth, 14” diameter. Used on SBC and BBC, 400ci and larger
There are 3 clutch sizes:
10.4”; the most common (aka the “10 1/2” clutch)
11”
12”; for truck applications
The 10.4” and 11” clutch can be used on either flywheel, and your choice depends on the clutch pressure plate bolt pattern. Generally, the 11” clutch will only fit on a 168 tooth flywheel, however, aftermarket companies do sell a pressure plate for the 153 tooth flywheel and and 11” disc.
What the heck?
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
Just throwing this out-
With only 5 miles on it, it's hard to believe there is already a 'wear' pattern. Are you sure it isn't perhaps burn marks from some grease etc that got on the flywheel or disc?
Looks like I see some grease on the splines of the disk- Is it possible you perhaps had a bit too much and it contaminated the disc when it flew off at speed? That would cause chattering.
Just trying to rule out the obvious.
With only 5 miles on it, it's hard to believe there is already a 'wear' pattern. Are you sure it isn't perhaps burn marks from some grease etc that got on the flywheel or disc?
Looks like I see some grease on the splines of the disk- Is it possible you perhaps had a bit too much and it contaminated the disc when it flew off at speed? That would cause chattering.
Just trying to rule out the obvious.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
It appears to be contamination; clean both the disk and the flywheel thoroughly with lacquer thinner and you should be ok. YMMV
FWIW: the Special High Perf BBCs also used the 153 tooth flywheel and 10.5" clutch disk. The reduced rotating inertia improves effective horsepower in a rapid acceleration.
FWIW: the Special High Perf BBCs also used the 153 tooth flywheel and 10.5" clutch disk. The reduced rotating inertia improves effective horsepower in a rapid acceleration.
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Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 39
From: Fremont CA
5 miles isn't long enough to establish anything. Flywheel looks good chatter can happen until parts wear and mate together. You machinist has used the proper DCM type flywheel surfacer and everything should bed in fine. Only thing you might want to be sure of is the pilot bearing in end of crank replaced?
Thread Starter
Instructor
Joined: Sep 2008
Posts: 216
Likes: 0
From: Eugene OR
Just a quick follow-up...
Putting her back together didn't help - I got a warranty replacement clutch (GREAT customer service from Summit, BTW) and slapped it in yesterday. After chasing around a bit of electrical nonsense everything is running today and not making funny noises. Time to take her down off my makeshift car lift and go for a drive!
After the lawn gets mowed.
And after the kitchen faucet gets replaced
And after the front sidewalk gets weeded.
Dammit!
Thanks to everybody for their guidance! I wouldn't be as far along with this car as I am without everybody's help here.
Putting her back together didn't help - I got a warranty replacement clutch (GREAT customer service from Summit, BTW) and slapped it in yesterday. After chasing around a bit of electrical nonsense everything is running today and not making funny noises. Time to take her down off my makeshift car lift and go for a drive!
After the lawn gets mowed.
And after the kitchen faucet gets replaced
And after the front sidewalk gets weeded.
Dammit!
Thanks to everybody for their guidance! I wouldn't be as far along with this car as I am without everybody's help here.